Exchange Surfaces Flashcards
why doesn’t diffusion work for multicellular organisms as a gaseous exhange system(3)
- higher metabolic activity
- distance between cels and supply of O2 is too far to be effective
- small SA: V ratio
why diffusion works for single cellular organisms for a gaseous exhange system? (2)
- metabolic activity of organism is low
- large SA:V ratio
The bigger the organism, the …. the SA:V ratio
smaller
name 4 features of a good gas exchange surface
- large surface area
- thin layers
- good blood supply
- ventilation
what feature of a good gaseous exchange system gives more space for molecules to pass through membrane
large surface area
what feature of a good gaseous exchange system reduces diffusion distance
thin layers
what 2 features of a good gaseous exchange system maintains a steep concentration gradient
good blood supply & ventilation
give 4 examples of a good exchange surfaces?
root hair cell, alveoli in lungs, gills in fish, villi in small intestine
how is nose adapted for efficient gaseos exhange
- good blood supply warms the air to body temperature (1);
hairy lining secretes mucus = prevents infection(1);
moist surfaces increase the humidity of incoming air, reducing evaporation from exchange
surfaces (1) and produces air at similar temperature and humidity to air already in lungs
why are smokers more likely to be affected by respiratory diseases
in smokers cilia anaesthetised so do not beat (1); mucus with its load of
bacteria and dust moves down into the lungs (1); more pathogens reach lungs so smokers more likely
to get infections of breathing system than non-smokers with active cilia
trachea function
tube carries air into luncgs from mouth / nasal cavity
trachea structure
supported by C-SHAPED Rings of cartilage (1) lined with ciliated epithelium cells and goblet cells(2) and contains smooth muscle and elastic fibres (3)
Name the type of epithelium in the walls of the air sacs
squamous epithelium
what do squamous epithelium produce to reduce surface tension in alveoili
surfacant
what does surfacant produced by epithelium do
reduce surface tension & prevent alveoli collapse
